JP7073246B2 - Phase shift mask blank, manufacturing method of phase shift mask, and manufacturing method of display device - Google Patents

Description

The present invention relates to a phase shift mask blank, a method for manufacturing a phase shift mask using the same, and a method for manufacturing a display device.

In recent years, display devices such as FPDs (Flat Panel Display) represented by LCDs (Liquid Crystal Display) are rapidly increasing in definition and high speed as well as increasing the screen size and wide viewing angle. One of the elements necessary for high-definition and high-speed display is the production of electronic circuit patterns such as elements and wiring that are fine and have high dimensional accuracy. Photolithography is often used for patterning of electronic circuits for display devices. Therefore, there is a need for a phase shift mask for manufacturing a display device in which a fine and highly accurate pattern is formed.

For example, Patent Document 1 describes a thin film containing molybdenum silicide as an etching solution obtained by diluting phosphoric acid, hydrogen peroxide, and ammonium fluorochloride with water so that damage to the transparent substrate is minimized during wet etching. A blank mask for a flat panel display that wet-etches a thin film containing molybdenum and a photo mask using the blank mask are disclosed.
Further, in Patent Document 2, for the purpose of improving the precision of the pattern, the phase inversion film 104 is composed of films having different compositions that can be etched into the same etching solution, and each film having a different composition is 1 Disclosed are phase-reversed blank masks and photomasks formed in the form of at least two or more multilayer films or continuous films laminated one or more times.

Korean Patent Application Publication No. 10-2016-0024204 Japanese Unexamined Patent Publication No. 2017-167512

In recent years, as a phase shift mask blank for manufacturing this type of display device, in order to reliably transfer a fine pattern of less than 2.0 μm, the transmission of the phase shift film to the exposure light is 10% or more, and further 20%. As a phase shift film having the above optical characteristics, it has been studied to use a phase shift film containing oxygen at a certain ratio or more (5 atomic% or more, further 10 atomic% or more). However, when a phase shift film having such an oxygen content of 5 atomic% or more, further 10 atomic% or more is patterned by wet etching, the phase shift film and the etching mask film formed on the phase shift film are used. It was found that the wet etching solution penetrated into the interface and the etching of the interface portion proceeded quickly. The cross-sectional shape of the edge portion of the formed phase shift film pattern became a tapered shape with an inclination and a hem.

When the cross-sectional shape of the edge portion of the phase shift film pattern is a tapered shape, the phase shift effect diminishes as the film thickness of the edge portion of the phase shift film pattern decreases. Therefore, the phase shift effect cannot be sufficiently exerted, and a fine pattern of less than 2.0 μm cannot be stably transferred. When the oxygen content in the phase shift film is 5 atomic% or more, and further 10 atomic% or more, it is difficult to strictly control the cross-sectional shape of the edge portion of the phase shift film pattern, and the line width (CD) is controlled. It was very difficult to do.

Therefore, the present invention has been made in view of the above-mentioned problems, and is a phase shift mask blank having a high permeability capable of patterning a phase shift film into a cross-sectional shape capable of sufficiently exhibiting the phase shift effect by wet etching. It is an object of the present invention to provide a method for manufacturing a phase shift mask having a phase shift film pattern capable of sufficiently exhibiting the phase shift effect, and a method for manufacturing a display device using the phase shift mask.

In order to solve these problems, the present inventors have diligently studied a method of verticalizing the cross-sectional shape of the edge portion of the phase shift film pattern. As a result of experiments and discussions on the state of the interface between the transition metal, silicon, the phase shift film containing oxygen, and the etching mask film, the transition existing at the interface between the phase shift film and the etching mask film. We found that metal oxides are the cause of infiltration. Then, the present inventor further investigated, and in the composition gradient region formed at the interface with the phase shift film, the region where the ratio of oxygen gradually and / or continuously increases in the depth direction. The phase shift film and the etching mask film are formed so that the content ratio of oxygen to silicon over a region at a depth of 10 nm from the interface between the phase shift film and the etching mask film is 3.0 or less. It was found that this can suppress the oxide of the transition metal existing at the interface and suppress the infiltration at the interface. The present invention has been made as a result of diligent studies as described above, and has the following configurations.

(Structure 1) A phase shift mask blank having a phase shift film on a transparent substrate and an etching mask film on the phase shift film.
The phase shift mask blank uses an etching mask film pattern in which a desired pattern is formed on the etching mask film as a mask, and the phase shift film is wet-etched to have a phase shift film pattern on the transparent substrate. It is the original plate for forming
The phase shift film contains a transition metal, silicon, and oxygen, and the oxygen content is 5 atomic% or more and 70 atomic% or less.
A composition gradient region is formed at the interface between the phase shift film and the etching mask film, and in the composition gradient region, the proportion of oxygen is gradually and / or continuously increased in the depth direction. Including area
A phase shift mask blank characterized in that the content ratio of oxygen to silicon over a region at a depth of 10 nm from the interface between the phase shift film and the etching mask film is 3.0 or less.

(Structure 2) The phase shift mask blank according to the configuration 1, wherein the phase shift film is composed of a plurality of layers.

(Structure 3) The phase shift mask blank according to the configuration 1, wherein the phase shift film is composed of a single layer.

(Structure 4) The phase shift mask blank according to any one of configurations 1 to 3, wherein the phase shift film contains nitrogen.

(Structure 5) The phase shift mask blank according to any one of configurations 1 to 4, wherein the phase shift film has a nitrogen content of 2 atomic% or more and 60 atomic% or less.

(Structure 6) The phase shift mask blank according to any one of configurations 1 to 5, wherein the film stress of the phase shift film is 0.2 GPa or more and 0.8 GPa or less.

(Structure 7) The phase shift mask blank according to any one of configurations 1 to 6, wherein the etching mask film is composed of a chromium-based material.

(Structure 8) The phase shift mask blank according to any one of configurations 1 to 7, wherein the etching mask film contains at least one of nitrogen, oxygen, and carbon.

(Structure 9) The phase shift mask according to any one of configurations 1 to 8, wherein the transparent substrate is a rectangular substrate, and the length of the short side of the transparent substrate is 300 mm or more. blank.

(Structure 10) The step of preparing the phase shift mask blank according to any one of configurations 1 to 9 and
The step of forming a resist film on the phase shift mask blank and
A resist film pattern is formed by drawing and developing a desired pattern on the resist film, and the etching mask film is patterned by wet etching using the resist film pattern as a mask to form the etching mask film pattern. And the process to do
A method for manufacturing a phase shift mask, which comprises a step of forming a phase shift film pattern on the transparent substrate by wet etching the phase shift film using the etching mask film pattern as a mask.

(Structure 11) The phase shift manufactured by using the phase shift mask manufactured by using the phase shift mask blank according to any one of configurations 1 to 9 or by the method for manufacturing the phase shift mask according to the configuration 10. A method for manufacturing a display device, which comprises a step of exposing and transferring a transfer pattern to a resist film on the display device using a mask.

According to the phase shift mask blank according to the present invention, a phase shift mask blank capable of patterning a phase shift film into a cross-sectional shape capable of sufficiently exhibiting the phase shift effect and having a high transmittance can be obtained by wet etching. Further, by wet etching, it is possible to obtain a phase shift mask blank capable of patterning a phase shift film into a cross-sectional shape having a small CD variation.

Further, according to the method for manufacturing a phase shift mask according to the present invention, the phase shift mask is manufactured by using the above-mentioned phase shift mask blank. Therefore, it is possible to manufacture a phase shift mask having a phase shift film pattern capable of sufficiently exhibiting the phase shift effect. Further, it is possible to manufacture a phase shift mask having a phase shift film pattern having a small CD variation. This phase shift mask can cope with the miniaturization of line-and-space patterns and contact holes.

Further, according to the method for manufacturing a display device according to the present invention, a phase shift mask manufactured by using the above-mentioned phase shift mask blank or a phase shift mask obtained by the above-mentioned method for manufacturing a phase shift mask is used for display. Manufacture the equipment. Therefore, it is possible to manufacture a display device having a fine line and space pattern or a contact hole.

It is a schematic diagram which shows the film structure of a phase shift mask blank. It is a schematic diagram which shows the manufacturing process of a phase shift mask. It is a figure which shows the composition analysis result in the depth direction with respect to the phase shift mask blank of Example 1. FIG. It is sectional drawing of the phase shift mask of Example 1. FIG. It is a figure which shows the composition analysis result in the depth direction with respect to the phase shift mask blank of the comparative example 1. FIG. It is a cross-sectional photograph of the phase shift mask of Comparative Example 1. It is a figure which shows the ratio of O / Si (the content ratio of oxygen with respect to silicon) in the depth direction by XPS with respect to the phase shift mask blank of Example 1 and Comparative Example 1. FIG. It is a figure which shows the composition analysis result in the depth direction with respect to the phase shift mask blank of Example 2. FIG. It is sectional drawing of the phase shift mask of Example 2. It is a figure which shows the ratio of O / Si in the depth direction (the content ratio of oxygen with respect to silicon) by XPS with respect to the phase shift mask blank of Examples 2 and 3. It is a figure which shows the composition analysis result in the depth direction with respect to the phase shift mask blank of Example 3. FIG. It is sectional drawing of the phase shift mask of Example 3. FIG.

Embodiment 1.
In the first embodiment, the phase shift mask blank will be described. This phase shift mask blank forms a phase shift mask having a phase shift film pattern on a transparent substrate by wet etching the phase shift film using the etching mask film pattern in which a desired pattern is formed on the etching mask film as a mask. The original version for.

FIG. 1 is a schematic diagram showing the film configuration of the phase shift mask blank 10.
The phase shift mask blank 10 shown in FIG. 1 includes a transparent substrate 20, a phase shift film 30 formed on the transparent substrate 20, and an etching mask film 40 formed on the phase shift film 30.

The transparent substrate 20 is transparent to the exposure light. The transparent substrate 20 has a transmittance of 85% or more, preferably 90% or more with respect to the exposure light, assuming that there is no surface reflection loss. The transparent substrate 20 is made of a material containing silicon and oxygen, and is made of a glass material such as synthetic quartz glass, quartz glass, aluminosilicate glass, soda lime glass, and low thermal expansion glass (SiO ₂ -TiO ₂ glass, etc.). Can be done. When the transparent substrate 20 is made of low thermal expansion glass, it is possible to suppress a change in the position of the phase shift film pattern due to thermal deformation of the transparent substrate 20. Further, the transparent substrate 20 for a phase shift mask blank used in a display device application is generally a rectangular substrate, and the length of the short side of the transparent substrate is 300 mm or more. According to the present invention, even if the length of the short side of the transparent substrate is as large as 300 mm or more, a fine phase shift film pattern of less than 2.0 μm formed on the transparent substrate can be stably transferred. A phase shift mask blank that can provide a possible phase shift mask.

The phase shift film 30 is composed of a transition metal silicide-based material containing a transition metal, silicon, and oxygen. As the transition metal, molybdenum (Mo), tantalum (Ta), tungsten (W), titanium (Ti), zirconium (Zr) and the like are suitable. Further, the phase shift film 30 may contain nitrogen. When nitrogen is contained, the refractive index can be increased, so that the film thickness for obtaining the phase difference can be reduced, which is preferable. Further, if the content of nitrogen contained in the phase shift film 30 is increased, the absorption coefficient of the complex refractive index becomes large, and high transmittance cannot be realized. The nitrogen content in the phase shift film 30 is preferably 2 atomic% or more and 60 atomic% or less. More preferably, it is 2 atomic% or more and 50 atomic% or less, and further preferably 5 atomic% or more and 30 atomic% or less.
Examples of the transition metal silicide-based material include an oxide of the transition metal silicide, an oxide nitride of the transition metal silicide, an oxide carbide of the transition metal silicide, and an oxide nitride carbide of the transition metal silicide. Further, when the transition metal silicide-based material is a molybdenum silicide-based material (MoSi-based material), a zirconium silicide-based material (ZrSi-based material), or a molybdenum zirconium silicide-based material (MoZrSi-based material), an excellent pattern cross section by wet etching is used. It is preferable in that the shape can be easily obtained.
The phase shift film 30 has a function of adjusting the reflectance for light incident from the transparent substrate 20 side (hereinafter, may be referred to as a back surface reflectance) and a function of adjusting the transmittance and the phase difference with respect to the exposed light. Has.
The phase shift film 30 can be formed by a sputtering method.

The transmittance of the phase shift film 30 with respect to the exposure light satisfies the value required for the phase shift film 30. The transmittance of the phase shift film 30 is preferably 10% to 70%, more preferably 15% to 65%, with respect to light having a predetermined wavelength contained in the exposure light (hereinafter referred to as a representative wavelength). It is more preferably 20% to 60%. That is, when the exposure light is a composite light containing light in a wavelength range of 313 nm or more and 436 nm or less, the phase shift film 30 has the above-mentioned transmittance with respect to the light of the representative wavelength included in the wavelength range. For example, when the exposure light is a composite light including i-line, h-line and g-line, the phase shift film 30 has the above-mentioned transmittance for any of i-line, h-line and g-line.
The transmittance of the phase shift film 30 can be adjusted by the atomic ratio of the transition metal and silicon contained in the phase shift film 30. In order to make the transmittance of the phase shift film 30 the above transmittance, the atomic ratio of the transition metal to silicon is configured to be 1: 1 or more and 1:15 or less. In order to enhance the chemical resistance (cleaning resistance) of the phase shift film 30, the atomic ratio of the transition metal to silicon is preferably 1: 2 or more and 1:15 or less, more preferably 1: 4 or more and 1:10 or less. desirable.
The transmittance can be measured using a phase shift amount measuring device or the like.

The phase difference of the phase shift film 30 with respect to the exposure light satisfies the value required for the phase shift film 30. The phase difference of the phase shift film 30 is preferably 160 ° to 200 °, and more preferably 170 ° to 190 ° with respect to the light of the representative wavelength contained in the exposure light. Due to this property, the phase of the light of the representative wavelength contained in the exposure light can be changed by 160 ° to 200 °. Therefore, a phase difference of 160 ° to 200 ° occurs between the light having the representative wavelength transmitted through the phase shift film 30 and the light having the representative wavelength transmitted only through the transparent substrate 20. That is, when the exposure light is a composite light containing light in a wavelength range of 313 nm or more and 436 nm or less, the phase shift film 30 has the above-mentioned phase difference with respect to the light of the representative wavelength included in the wavelength range. For example, when the exposure light is a composite light including i-line, h-line, and g-line, the phase shift film 30 has the above-mentioned phase difference with respect to any of i-line, h-line, and g-line.
The phase difference can be measured by using a phase shift amount measuring device or the like.

The back surface reflectance of the phase shift film 30 is 15% or less, preferably 10% or less in the wavelength range of 365 nm to 436 nm. Further, the back surface reflectance of the phase shift film 30 is preferably 20% or less, more preferably 17% or less, with respect to the light in the wavelength range of 313 nm to 436 nm when the exposure light contains j-line. More preferably, it is 15% or less. Further, the back surface reflectance of the phase shift film 30 is preferably 0.2% or more in the wavelength range of 365 nm to 436 nm, and preferably 0.2% or more with respect to light in the wavelength range of 313 nm to 436 nm.
The back surface reflectance can be measured using a spectrophotometer or the like.

The content of oxygen contained in the phase shift film 30 so that the phase shift film 30 has the above-mentioned phase difference and transmittance, and if necessary, the phase-shift film 30 has the above-mentioned back surface reflectance. Is adjusted. Specifically, the phase shift film 30 is configured so that the oxygen content is 5 atomic% or more and 70 atomic% or less. The content of oxygen contained in the phase shift film 30 is preferably 10 atomic% or more and 70 atomic% or less. The phase shift film 30 may be composed of a plurality of layers or may be composed of a single layer. The phase shift film 30 composed of a single layer is preferable because it is difficult for an interface to be formed in the phase shift film 30 and it is easy to control the cross-sectional shape. On the other hand, the phase shift film 30 composed of a plurality of layers is preferable in terms of ease of film formation and the like.
Further, the light elements of nitrogen and oxygen contained in the phase shift film 30 are increased or decreased stepwise or continuously even if they are uniformly contained in the film thickness direction of the phase shift film 30. Is also good. It is preferable that the nitrogen content and the oxygen content are the above-mentioned predetermined contents in the region of 50% or more of the film thickness of the phase shift film 30.
Further, the phase shift film 30 of the phase shift mask blank 10 is required to have high chemical resistance (cleaning resistance). In order to increase the chemical resistance (cleaning resistance) of the phase shift film 30, it is effective to increase the film density. There is a correlation between the film density of the phase shift film 30 and the film stress, and in consideration of chemical resistance (cleaning resistance), the film stress of the phase shift film 30 is preferably high. On the other hand, for the film stress of the phase shift film 30, it is necessary to consider the positional shift when the phase shift film pattern is formed and the loss of the phase shift film pattern. From the above viewpoint, the film stress of the phase shift film 30 is preferably 0.2 GPa or more and 0.8 GPa or less, and more preferably 0.4 GPa or more and 0.8 GPa or less.

The etching mask film 40 is arranged on the upper side of the phase shift film 30, and is made of a material having etching resistance to the etching solution for etching the phase shift film 30. Further, the etching mask film 40 may have a function of blocking the transmission of exposure light, and further, the film surface reflectance of the phase shift film 30 with respect to the light incident from the phase shift film 30 side is 350 nm to 436 nm. The etching mask film 40, which may have a function of reducing the film surface reflectance so as to be 15% or less in the wavelength range, is made of, for example, a chromium-based material. More specifically, as a chromium-based material, a material containing chromium (Cr) or chromium (Cr) and at least one of oxygen (O), nitrogen (N), and carbon (C). Can be mentioned. Alternatively, a material containing chromium (Cr) and at least one of oxygen (O), nitrogen (N), and carbon (C), and further containing fluorine (F) can be mentioned. For example, examples of the material constituting the etching mask film 40 include Cr, CrO, CrN, CrF, CrCO, CrCN, CrON, CrCON, and CrCONF.
The etching mask film 40 can be formed by a sputtering method.

When the etching mask film 40 has a function of blocking the transmission of the exposure light, the optical density with respect to the exposure light is preferably 3 or more, more preferably, in the portion where the phase shift film 30 and the etching mask film 40 are laminated. It is 3.5 or more, more preferably 4 or more.
The optical density can be measured using a spectrophotometer, an OD meter, or the like.

The etching mask film 40 may be composed of a single film having a uniform composition depending on the function, may be composed of a plurality of films having different compositions, or may have a composition in the thickness direction. It may consist of a single membrane that changes continuously.

The phase shift mask blank 10 shown in FIG. 1 has an etching mask film 40 on the phase shift film 30, but has an etching mask film 40 on the phase shift film 30 and a resist film on the etching mask film 40. The present invention can also be applied to a phase shift mask blank provided with.

Further, in the phase shift mask blank 10, a composition gradient region is formed at the interface between the phase shift film 30 and the etching mask film 40, and in the composition gradient region, the ratio of oxygen is stepwise and / or toward the depth direction. Alternatively, it is configured to include a continuously increasing region. More specifically, in the composition gradient region, the ratio of oxygen is stepwise and / or continuously in the depth direction toward the transparent substrate 20 from at least the interface between the phase shift film 30 and the etching mask film 40. It has an increasing area.
The phase shift mask blank 10 is configured such that the content ratio of oxygen to silicon over a region at a depth of 10 nm from the interface between the phase shift film 30 and the etching mask film 40 is 3.0 or less. .. At this interface, when the composition of the phase shift mask blank 10 is analyzed by X-ray photoelectron spectroscopy, the proportion of transition metals decreases from the phase shift film 30 toward the etching mask film 40, and the content of transition metals decreases for the first time. Is a position where is 0 atomic%.
The oxygen content ratio to silicon in the region at a depth of 10 nm from the interface between the phase shift film 30 and the etching mask film 40 is required to be 3.0 or less, preferably 2.8 or less. It is more preferably 2.5 or less, and even more preferably 2.0 or less. From the viewpoint of film quality continuity between the phase shift film 30 and the composition gradient region, the oxygen content ratio to silicon is preferably 0.3 or more, and more preferably 0.5 or more. preferable.

Next, a method of manufacturing the phase shift mask blank 10 of this embodiment will be described. The phase shift mask blank 10 shown in FIG. 1 is manufactured by performing the following phase shift film forming step and etching mask film forming step.
Hereinafter, each step will be described in detail.

1. 1. Phase shift film forming step First, the transparent substrate 20 is prepared. The transparent substrate 20 is made of any glass material such as synthetic quartz glass, quartz glass, aluminosilicate glass, soda lime glass, and low thermal expansion glass (SiO ₂ -TiO ₂ glass, etc.) as long as it is transparent to the exposure light. It may be what is done.

Next, the phase shift film 30 is formed on the transparent substrate 20 by a sputtering method.
The film formation of the phase shift film 30 is performed by using a sputter target containing a transition metal and silicon, which are the main components of the material constituting the phase shift film 30, or a sputter target containing a transition metal, silicon, oxygen and / or nitrogen. For example, a spatter gas atmosphere composed of an inert gas containing at least one selected from the group consisting of helium gas, neon gas, argon gas, krypton gas and xenone gas, or the above-mentioned inert gas and oxygen gas, carbon dioxide gas, and the like. It is carried out in a sputter gas atmosphere consisting of a mixed gas with an active gas containing at least one selected from the group consisting of nitrogen monoxide gas and nitrogen dioxide gas.

The composition and thickness of the phase shift film 30 are adjusted so that the phase shift film 30 has the above-mentioned phase difference and transmittance. The composition of the phase shift film 30 can be controlled by the content ratio of the elements constituting the sputter target (for example, the ratio of the content of the transition metal to the content of silicon), the composition of the sputter gas, the flow rate, and the like. The thickness of the phase shift film 30 can be controlled by the sputtering power, the sputtering time, and the like. Further, when the sputtering apparatus is an in-line type sputtering apparatus, the thickness of the phase shift film 30 can be controlled by the transfer speed of the substrate. In this way, control is performed so that the oxygen content of the phase shift film 30 is 5 atomic% or more and 70 atomic% or less.

When the phase shift film 30 is composed of a single film having a uniform composition, the above-mentioned film forming process is performed only once without changing the composition and flow rate of the sputter gas. When the phase shift film 30 is composed of a plurality of films having different compositions, the above-mentioned film forming process is performed a plurality of times by changing the composition and flow rate of the sputter gas for each film forming process. The phase shift film 30 may be formed by using targets having different content ratios of elements constituting the sputtering target. When the phase shift film 30 is composed of a single film whose composition changes continuously in the thickness direction, the above-mentioned film forming process is performed while changing the composition and flow rate of the sputter gas with the elapsed time of the film forming process. Do it only once. When the film forming process is performed a plurality of times, the sputtering power applied to the sputtering target can be reduced.

2. 2. Surface treatment step The surface of the phase shift film 30 after forming the phase shift film 30 made of a transition metal silicide material containing a transition metal, silicon, and oxygen is easily oxidized, and an oxide of the transition metal is easily generated. .. In order to suppress the infiltration by the etching solution due to the presence of the oxide of the transition metal, a surface treatment step for adjusting the state of surface oxidation of the phase shift film 30 is performed.
Examples of the surface treatment step for adjusting the surface oxidation state of the phase shift film 30 include a method of surface treatment with an acidic aqueous solution, a method of surface treatment with an alkaline aqueous solution, and a method of surface treatment with a dry treatment such as ashing. ..
After the etching mask film forming step described later, a composition gradient region is formed at the interface between the phase shift film 30 and the etching mask film 40, and the proportion of oxygen in the composition gradient region is stepwise and gradually toward the depth direction. / Or if it contains a continuously increasing region and the oxygen content to silicon over the region at a depth of 10 nm from the interface between the phase shift film 30 and the etching mask film 40 is 3.0 or less. , Any surface treatment step may be performed.
For example, in the method of surface-treating with an acidic aqueous solution and the method of surface-treating with an alkaline aqueous solution, the surface oxidation state of the phase shift film 30 can be adjusted by appropriately adjusting the concentration, temperature, and time of the acidic or alkaline aqueous solution. Can be adjusted. As a method of surface-treating with an acidic aqueous solution and a method of surface-treating with an alkaline aqueous solution, a method of immersing a substrate with a phase-shift film in which a phase-shift film 30 is formed on a transparent substrate 20 in the above-mentioned aqueous solution, or a method of phase-shifting is performed. Examples thereof include a method in which the aqueous solution is brought into contact with the film 30.
3. 3. Etching Mask Film Forming Step After surface treatment for adjusting the surface oxidation state of the surface of the phase shift film 30, the etching mask film 40 is formed on the phase shift film 30 by a sputtering method.
In this way, the phase shift mask blank 10 is obtained.

The film formation of the etching mask film 40 uses a sputter target containing chromium or a chromium compound (chromium oxide, chromium nitride, chromium carbide, chromium oxide nitride, chromium nitride carbide, etc.), for example, helium gas, neon gas, argon. A sputter gas atmosphere consisting of an inert gas containing at least one selected from the group consisting of gas, krypton gas and xenone gas, or at least one selected from the group consisting of helium gas, neon gas, argon gas, krypton gas and xenone gas. From a mixed gas of an inert gas containing at least one selected from the group consisting of oxygen gas, nitrogen gas, nitrogen monoxide gas, nitrogen dioxide gas, carbon dioxide gas, hydrocarbon gas, and fluorine gas. It is performed in a spatter gas atmosphere. Examples of the hydrocarbon gas include methane gas, butane gas, propane gas, styrene gas and the like.

When the etching mask film 40 is composed of a single film having a uniform composition, the above-mentioned film forming process is performed only once without changing the composition and flow rate of the sputter gas. When the etching mask film 40 is composed of a plurality of films having different compositions, the above-mentioned film forming process is performed a plurality of times by changing the composition and flow rate of the spatter gas for each film forming process. When the etching mask film 40 is composed of a single film whose composition changes continuously in the thickness direction, the above-mentioned film forming process is performed while changing the composition and flow rate of the sputter gas with the elapsed time of the film forming process. Do it only once.

By performing the film forming process of the phase shift film 30 and the etching mask film 40 and the surface treatment for adjusting the surface oxidation state of the surface of the phase shift film 30 in this way, the phase shift film 30 and the etching mask film 40 can be combined. A composition gradient region is formed at the interface, and the composition gradient region includes a region in which the proportion of oxygen is gradually and / or continuously increases in the depth direction, and the phase shift film and the etching mask film are included. The phase shift film 30 and the etching mask film 40 can be formed so that the oxygen content ratio to silicon over a region having a depth of 10 nm from the interface with the surface is 3.0 or less.

Although the surface treatment for adjusting the surface oxidation state of the surface of the phase shift film 30 has been described, in the film formation process of the phase shift film 30, the surface of the phase shift film 30 is surface-oxidized in the latter half of the film formation process. A region in which the proportion of oxygen in the composition gradient region is gradually and / or continuously increased in the depth direction by changing to a difficult gas type or adding the gas type is included. The oxygen content ratio to silicon over a region at a depth of 10 nm from the interface between the phase shift film and the etching mask film may be 3.0 or less.

Since the phase shift mask blank 10 shown in FIG. 1 includes the etching mask film 40 on the phase shift film 30, an etching mask film forming step is performed when the phase shift mask blank 10 is manufactured. Further, when manufacturing a phase shift mask blank having an etching mask film 40 on the phase shift film 30 and a resist film on the etching mask film 40, a resist film is formed on the etching mask film 40 after the etching mask film forming step. Form.

In the phase shift mask blank 10 of the first embodiment, a composition inclination region is formed at the interface between the phase shift film 30 and the etching mask film 40, and in the composition inclination region, the ratio of oxygen is directed toward the depth direction. The oxygen content to silicon over a region at a depth of 10 nm from the interface between the phase shift film and the etching mask film, including regions that are increasing stepwise and / or continuously, is such that the oxygen content is 3.0 or less. In addition, the phase shift film 30 and the etching mask film 40 are configured. As a result, the infiltration of the etching solution at the interface between the phase shift film 30 and the etching mask film 40 can be effectively suppressed, the phase shift can contribute to the verticalization of the pattern cross section, and the phase shift has excellent CD uniformity. It is possible to obtain a phase shift mask in which a film pattern is formed. Further, in the phase shift mask, when the etching mask film pattern remains on the phase shift film pattern, the influence of reflection from the pellicle attached to the phase shift mask or the display device substrate can be suppressed. Further, the phase shift mask blank 10 of the first embodiment has a good cross-sectional shape, and a phase shift film pattern having a small CD variation and a high transmittance can be formed by wet etching. Therefore, a phase shift mask blank capable of producing a phase shift mask capable of accurately transferring a high-definition phase shift film pattern can be obtained.

Embodiment 2.
In the second embodiment, a method of manufacturing a phase shift mask will be described.

FIG. 2 is a schematic diagram showing a method of manufacturing a phase shift mask.
The method for manufacturing a phase shift mask shown in FIG. 2 is a method for manufacturing a phase shift mask using the phase shift mask blank 10 shown in FIG. 1, and is a step of forming a resist film on the following phase shift mask blank 10. A resist film pattern 50 is formed by drawing and developing a desired pattern on the resist film (first resist film pattern forming step), and the resist film pattern 50 is used as a mask and an etching mask film is wet-etched. A step of patterning 40 to form an etching mask film pattern 40a (first etching mask film pattern forming step) and a phase shift film 30 on a transparent substrate 20 by wet etching using the etching mask film pattern 40a as a mask. Includes a step of forming the phase shift film pattern 30a (phase shift film pattern forming step). Then, a second resist film pattern forming step and a second etching mask film pattern forming step are further included.
Hereinafter, each step will be described in detail.

1. 1. First Resist Film Pattern Forming Step In the first resist film pattern forming step, first, a resist film is formed on the etching mask film 40 of the phase shift mask blank 10 of the first embodiment. The resist film material used is not particularly limited. For example, it may be sensitive to laser light having any wavelength selected from the wavelength range of 350 nm to 436 nm described later. Further, the resist film may be either a positive type or a negative type.
Then, a desired pattern is drawn on the resist film using a laser beam having any wavelength selected from the wavelength range of 350 nm to 436 nm. The pattern drawn on the resist film is a pattern formed on the phase shift film 30. Examples of the pattern drawn on the resist film include a line-and-space pattern and a hole pattern.
Then, the resist film is developed with a predetermined developer to form a first resist film pattern 50 on the etching mask film 40 as shown in FIG. 2 (a).

2. 2. First Etching Mask Film Pattern Forming Step In the first etching mask film pattern forming step, first, the etching mask film 40 is etched using the first resist film pattern 50 as a mask, and the first etching mask film pattern 40a is used. Form. The etching mask film 40 is formed of a chromium-based material containing chromium (Cr). The etching solution for etching the etching mask film 40 is not particularly limited as long as it can selectively etch the etching mask film 40. Specific examples thereof include an etching solution containing dimerium ammonium nitrate and perchloric acid.
Then, as shown in FIG. 2B, the first resist film pattern 50 is peeled off using a resist stripping solution or by ashing. In some cases, the next phase shift film pattern forming step may be performed without peeling off the first resist film pattern 50.

3. 3. Phase shift film pattern forming step In the first phase shift film pattern forming step, the phase shift film 30 is etched using the first etching mask film pattern 40a as a mask, and the phase is as shown in FIG. 2 (c). A shift film pattern 30a is formed. Examples of the phase shift film pattern 30a include a line-and-space pattern and a hole pattern. The etching solution for etching the phase shift film 30 is not particularly limited as long as it can selectively etch the phase shift film 30. For example, an etching solution containing ammonium fluoride, phosphoric acid and hydrogen peroxide, and an etching solution containing ammonium hydrogen fluoride and hydrogen chloride can be mentioned.

4. Second resist film pattern forming step In the second resist film pattern forming step, first, a resist film covering the first etching mask film pattern 40a is formed. The resist film material used is not particularly limited. For example, it may be sensitive to laser light having any wavelength selected from the wavelength range of 350 nm to 436 nm described later. Further, the resist film may be either a positive type or a negative type.
Then, a desired pattern is drawn on the resist film using a laser beam having any wavelength selected from the wavelength range of 350 nm to 436 nm. The pattern drawn on the resist film is a light-shielding band pattern that shields the outer peripheral region of the region where the pattern is formed on the phase shift film 30 from light, and a light-shielding band pattern that shields the central portion of the phase shift film pattern from light. The pattern drawn on the resist film may not have a light-shielding band pattern that shields the central portion of the phase-shift film pattern 30a from light depending on the transmittance of the phase-shift film 30 with respect to the exposure light.
Then, the resist film is developed with a predetermined developer to form a second resist film pattern 60 on the first etching mask film pattern 40a as shown in FIG. 2 (d).

5. Second Etching Mask Film Pattern Forming Step In the second etching mask film pattern forming step, the first etching mask film pattern 40a is etched using the second resist film pattern 60 as a mask, and FIG. 2 (e) shows. As shown, a second etching mask film pattern 40b is formed. The first etching mask film pattern 40a is formed of a chromium-based material containing chromium (Cr). The etching solution for etching the first etching mask film pattern 40a is not particularly limited as long as it can selectively etch the first etching mask film pattern 40a. For example, an etching solution containing dimerium ammonium nitrate and perchloric acid can be mentioned.
Then, the second resist film pattern 60 is peeled off using a resist stripping solution or by ashing.
In this way, the phase shift mask 100 is obtained.
In the above description, the case where the etching mask film 40 has a function of blocking the transmission of exposure light has been described, but the case where the etching mask film 40 has only the function of a hard mask when etching the phase shift film 30. In the above description, the second resist film pattern forming step and the second etching mask film pattern forming step are not performed, and after the phase shift film pattern forming step, the first etching mask film pattern is peeled off. , A phase shift mask 100 is manufactured.

According to the method for manufacturing a phase shift mask according to the second embodiment, since the phase shift mask blank according to the first embodiment is used, it is possible to form a phase shift film pattern having a good cross-sectional shape and small CD variation. .. Therefore, it is possible to manufacture a phase shift mask capable of accurately transferring a high-definition phase shift film pattern. The phase shift mask manufactured in this way can cope with the miniaturization of line-and-space patterns and contact holes.

Embodiment 3.
In the third embodiment, a method of manufacturing a display device will be described. The display device uses a phase shift mask 100 manufactured by using the phase shift mask blank 10 described above, or a step of using the phase shift mask 100 manufactured by the method of manufacturing the phase shift mask 100 described above (mask mounting step). ) And the step of exposing and transferring the transfer pattern to the resist film on the display device (pattern transfer step).
Hereinafter, each step will be described in detail.

1. 1. Mounting step In the mounting step, the phase shift mask manufactured in the second embodiment is mounted on the mask stage of the exposure apparatus. Here, the phase shift mask is arranged so as to face the resist film formed on the display device substrate via the projection optical system of the exposure device.

2. 2. Pattern transfer step In the pattern transfer step, the phase shift mask 100 is irradiated with exposure light to transfer the phase shift film pattern to the resist film formed on the display device substrate. The exposure light is a composite light containing light having a plurality of wavelengths selected from the wavelength range of 365 nm to 436 nm, or monochromatic light selected by cutting a certain wavelength range from the wavelength range of 365 nm to 436 nm with a filter or the like. For example, the exposure light is a composite light including i-line, h-line and g-line, or i-line monochromatic light. When composite light is used as the exposure light, the exposure light intensity can be increased and the throughput can be increased, so that the manufacturing cost of the display device can be reduced.

According to the method for manufacturing a display device according to the third embodiment, it is possible to manufacture a high-definition display device having high resolution, fine line-and-space patterns and contact holes, capable of suppressing CD errors.

Example 1.
A. Phase shift mask blank and its manufacturing method In order to manufacture the phase shift mask blank of Example 1, first, a synthetic quartz glass substrate of 1214 size (1220 mm × 1400 mm) was prepared as the transparent substrate 20.

Then, the synthetic quartz glass substrate was mounted on a tray (not shown) with the main surface facing downward, and carried into the chamber of the in-line sputtering apparatus.
In order to form the phase shift film 30 on the main surface of the transparent substrate 20, first, with the inside of the first chamber kept at a predetermined degree of vacuum, argon (Ar) gas, carbon dioxide gas (CO ₂ ), and nitrogen ( N ₂ ) A mixed gas with gas (Ar: 20 sccm, CO ₂ : 10 sccm, N ₂ : 20 sccm) was introduced, and 6.0 kW was introduced into the first sputter target containing molybdenum and silicon (molybdenum: silicon = 1: 4). Sputter power was applied and a carbide carbide of molybdenum silicide containing molybdenum, silicon, oxygen, nitrogen and carbon was deposited on the main surface of the transparent substrate 20 by reactive sputtering. Then, a phase shift film 30 having a film thickness of 202 nm was formed. Further, after forming the phase shift film 30 on the transparent substrate 20, the phase shift film 30 was taken out from the chamber, and the surface of the phase shift film 30 was surface-treated with an alkaline aqueous solution. The surface treatment conditions were an alkali concentration of 0.7%, a temperature of 30 degrees, and a surface treatment time of 1200 seconds.

Next, the transparent substrate 20 with the phase shift film 30 after the surface treatment is carried into the second chamber, and the inside of the second chamber is kept at a predetermined degree of vacuum, and argon (Ar) gas and nitrogen (N ₂ ) are brought into the second chamber. A mixed gas with gas (Ar: 65 sccm, N ₂ : 15 sccm) was introduced. Then, 1.5 kW of sputtering power was applied to the second sputtering target made of chromium, and chromium nitride (CrN) containing chromium and nitrogen was formed on the phase shift film 30 by reactive sputtering (thickness). 15 nm). Next, with the inside of the third chamber kept at a predetermined degree of vacuum, a mixed gas (30 sccm) of argon (Ar) gas and methane (CH ₄ : 4.9%) gas was introduced, and the third sputtering composed of chromium was introduced. A sputtering power of 8.5 kW was applied to the target, and a chromium carbide (CrC) containing chromium and carbon was formed on CrN by reactive sputtering (thickness: 60 nm). Finally, with the inside of the fourth chamber kept at a predetermined degree of vacuum, a mixed gas of argon (Ar) gas and methane (CH ₄ : 5.5%) gas, nitrogen (N ₂ ) gas, and oxygen (O ₂ ). A mixed gas with gas (Ar + CH ₄ : 30 sccm, N ₂ : 8 sccm, O ₂ : 3 sccm) was introduced, and 2.0 kW of sputter power was applied to the fourth sputter target made of chromium, and the sputter power was applied to CrC by reactive sputtering. Chromium carbide nitride (CrCON) containing chromium, carbon, oxygen and nitrogen was formed in (thickness: 30 nm). As described above, the etching mask film 40 having a laminated structure of the CrN layer, the CrC layer, and the CrCON layer was formed on the phase shift film 30.
In this way, a phase shift mask blank 10 in which the phase shift film 30 and the etching mask film 40 were formed on the transparent substrate 20 was obtained.

For the phase shift film 30 (phase shift film 30 whose surface of the phase shift film 30 is surface-treated with an alkaline aqueous solution) of the obtained phase shift mask blank 10, the transmission rate and phase difference are measured by MPM-100 manufactured by Lasertec. bottom. For the measurement of the transmittance and phase difference of the phase shift film 30, a substrate with a phase shift film 30 is formed on the main surface of a synthetic quartz glass substrate, which is manufactured by setting them on the same tray (a substrate with a phase shift film). Dummy substrate) was used. The transmittance and phase difference of the phase shift film 30 were measured by taking out the substrate with the phase shift film (dummy substrate) from the chamber before forming the etching mask film 40. As a result, the transmittance was 22.1% (wavelength: 365 nm) and the phase difference was 161 degrees (wavelength: 365 nm). The film thickness of the phase shift film 30 surface-treated with the alkaline aqueous solution decreased from the film thickness immediately after the film formation to 183 nm.
Further, the flatness change of the phase shift film 30 was measured using UltraFLAT 200M (manufactured by Corning TOPEL), and the film stress was calculated to be 0.46 GPa. The phase shift film 30 has a small amount of change in transmittance and a small amount of change in phase difference with respect to the chemicals (sulfuric acid hydrogen peroxide, ammonia hydrogen peroxide, ozone water) used for cleaning the phase shift mask, and has high chemical resistance and cleaning resistance. Had.

Further, the film surface reflectance and the optical density of the obtained phase shift mask blank were measured with a spectrophotometer SolidSpec-3700 manufactured by Shimadzu Corporation. The film surface reflectance of the phase shift mask blank (etching mask film 40) was 8.3% (wavelength: 436 nm), and the optical density OD was 4.0 (wavelength: 436 nm). It was found that this etching mask film functions as a light-shielding film having a low reflectance on the film surface.

Further, the obtained phase shift mask blank 10 was subjected to composition analysis in the depth direction by X-ray photoelectron spectroscopy (XPS). FIG. 3 shows the composition analysis result in the depth direction by XPS with respect to the phase shift mask blank of Example 1. FIG. 3 shows the composition analysis results of the etching mask film 40 on the phase shift film 30 side and the phase shift film 30 in the phase shift mask blank. The horizontal axis of FIG. 3 shows the depth (nm) of the phase shift mask blank 10 in terms of SiO ₂ with respect to the outermost surface of the etching mask film 40, and the vertical axis shows the content rate (atomic%). In FIG. 3, each curve shows changes in the content of silicon (Si), nitrogen (N), oxygen (O), carbon (C), chromium (Cr), and molybdenum (Mo), respectively.

As shown in FIG. 3, in the composition analysis result in the depth direction by XPS with respect to the phase shift mask blank 10, the interface between the phase shift film 30 and the etching mask film 40 (transition from the phase shift film 30 toward the etching mask film 40). The ratio of chromium decreases from the etching mask film 40 toward the phase shift film 30 at the position where the content of transition metal becomes 0 atom% for the first time when the ratio of metal decreases), and the content of chromium becomes 0 atom for the first time. In the composition gradient region, which is a region up to the% position, the proportion of oxygen caused by the phase shift film 30 gradually and / or continuously increases monotonically toward the depth direction.
Further, FIG. 7 is a diagram showing the ratio of O / Si (oxygen content ratio to silicon) in the depth direction by XPS to the phase shift mask blanks of Example 1 and Comparative Example 1. As shown in FIG. 7, the phase shift mask blank of Example 1 has a maximum value of the oxygen content ratio to silicon over a region at a depth of 10 nm from the interface between the phase shift film 30 and the etching mask film 40. It was 0 and was 3.0 or less. This interface is a transition metal (molybdenum in this case) from the phase shift film 30 toward the etching mask film 40 when the composition analysis of the phase shift mask blank 10 is performed from the etching mask film 40 side by X-ray photoelectron spectroscopy. The position is set so that the content of the transition metal becomes 0 atomic% for the first time when the ratio of

From the disappearance of chromium (Cr) caused by the etching mask film 40 to the appearance of the oxygen (O) peak caused by the transparent substrate 20 (before the molybdenum (Mo) caused by the phase shift film 30 sharply decreases). In the uniform composition region of the phase shift film 30 of), the molybdenum (Mo) content is 12 atomic% on average, the silicon (Si) content is 23 atomic% on average, and the nitrogen (N) content is 13 atomic% on average. The content of oxygen (O) was 40 atomic% on average, the content of carbon (C) was 12 atomic% on average, and the fluctuation of each content was 3 atomic% or less.

B. Phase shift mask and its manufacturing method In order to manufacture the phase shift mask 100 using the phase shift mask blank 10 manufactured as described above, first, a resist coating device is applied on the etching mask film 40 of the phase shift mask blank 10. A photoresist film was applied using.
Then, through the heating and cooling steps, a photoresist film having a film thickness of 520 nm was formed.
After that, a photoresist film is drawn using a laser drawing device, and after undergoing development and rinsing steps, a line-and-space pattern having a line pattern width of 1.8 μm and a space pattern width of 1.8 μm is placed on the etching mask film. The resist film pattern of was formed.

Then, using the resist film pattern as a mask, the etching mask film was wet-etched with a chromium etching solution containing dicerium ammonium nitrate and perchloric acid to form the first etching mask film pattern 40a.

Then, using the first etching mask film pattern 40a as a mask, the phase shift film 30 is wet-etched with a molybdenum silicide etching solution obtained by diluting a mixed solution of ammonium hydrogen fluoride and hydrogen peroxide with pure water to shift the phase. A film pattern 30a was formed.
Then, the resist film pattern was peeled off.

Then, using a resist coating apparatus, a photoresist film was applied so as to cover the first etching mask film pattern 40a.
Then, through the heating and cooling steps, a photoresist film having a film thickness of 520 nm was formed.
After that, a photoresist film was drawn using a laser drawing apparatus, and a second resist film pattern 60 for forming a light-shielding band was formed on the first etching mask film pattern 40a through development and rinsing steps. ..

Then, using the second resist film pattern 60 as a mask, the first etching mask film pattern 40a formed in the transfer pattern forming region is wet-etched with a chromium etching solution containing dicerium nitrate ammonium nitrate and perchloric acid. bottom.
Then, the second resist film pattern 60 was peeled off.

In this way, the phase shift mask 100 is formed on the transparent substrate 20 with a phase shift film pattern 30a in the transfer pattern forming region and a light-shielding band having a laminated structure of the phase shift film pattern 30a and the etching mask film pattern 40b. Obtained.

The cross section of the obtained phase shift mask was observed with a scanning electron microscope. In the following Example 1 and Comparative Example 1, a scanning electron microscope was used for observing the cross section of the phase shift mask. FIG. 4 is a cross-sectional photograph of the phase shift mask of the first embodiment.

As shown in FIG. 4, the phase shift film pattern formed on the phase shift mask of Example 1 had a cross-sectional shape close to vertical that could sufficiently exert the phase shift effect. Further, in the phase shift film pattern, no penetration was observed at either the interface with the etching mask film pattern and the interface with the substrate. In addition, it had a phase shift film pattern with a small hem width and small CD variation. Specifically, the cross section of the phase shift film pattern is composed of the upper surface, the lower surface and the side surface of the phase shift film pattern. In the cross section of this phase shift film pattern, the angle formed by the portion where the upper surface and the side surface are in contact (upper side) and the portion where the side surface and the lower surface are in contact (lower side) is 53 degrees. Therefore, a phase shift mask having an excellent phase shift effect in an exposure light containing light in a wavelength range of 300 nm or more and 500 nm or less, more specifically, a composite light including i-line, h-line and g-line. Obtained.
In addition, in the cross section of the phase shift film pattern of Example 1, the angle between the portion where the upper surface and the side surface are in contact (upper side) and the portion where the side surface and the lower surface are in contact (lower side) is 53 degrees, and the angle is 53 degrees. It exceeded the lower limit of 45 degrees, which allows cross-section control. Therefore, when the phase shift film pattern of Example 1 is formed, it is possible to further verticalize the cross-sectional shape by performing overetching.

The CD variation of the phase shift film pattern of the phase shift mask was measured by SIR8000 manufactured by Seiko Instruments Nanotechnology. The CD variation was measured at 11 × 11 points in a region of 1100 mm × 1300 mm excluding the peripheral region of the substrate. The CD variation is the deviation width from the target line-and-space pattern (line pattern width: 1.8 μm, space pattern width: 1.8 μm). In Example 1 and Comparative Example 1, the same device was used for measuring the CD variation.
The CD variation was as good as 0.096 μm.
Therefore, when the phase shift mask of Example 1 is set on the mask stage of the exposure apparatus and exposure-transferred to the resist film on the display apparatus, it can be said that a fine pattern of less than 2.0 μm can be transferred with high accuracy. ..

Example 2.
A. Phase shift mask blank and its manufacturing method In order to manufacture the phase shift mask blank of Example 2, a synthetic quartz glass substrate of 1214 size (1220 mm × 1400 mm) was prepared as the transparent substrate 20 in the same manner as in Example 1.

In order to form the phase shift film 30 on the main surface of the transparent substrate 20, first, with a predetermined degree of vacuum in the first chamber of the in-line sputtering apparatus, argon (Ar) gas and helium (He) gas are used. And a mixed gas of nitrogen (N ₂ ) gas (Ar: 18 sccm, He: 50 sccm, N ₂ : 13 sccm) was introduced, and 7 was introduced into the first sputter target (molybdenum: silicon = 1: 9) containing molybdenum and silicon. A sputter power of .6 kW was applied, and an oxide nitride of molybdenum silicide containing molybdenum, silicon, oxygen and nitrogen was deposited on the main surface of the transparent substrate 20 by reactive sputtering. Then, a phase shift film 30 having a film thickness of 150 nm was formed.

Next, after forming the phase shift film 30 on the transparent substrate 20, an etching mask having a laminated structure of a CrN layer, a CrC layer, and a CrCON layer on the phase shift film 30 without surface treatment is performed. The film 40 was formed.
In this way, a phase shift mask blank 10 in which the phase shift film 30 and the etching mask film 40 were formed on the transparent substrate 20 was obtained.

The transmittance and phase difference of the obtained phase shift mask blank phase shift film were measured by MPM-100 manufactured by Lasertec. For the measurement of the transmittance and phase difference of the phase shift film, a substrate with a phase shift film (dummy) in which the phase shift film 30 is formed on the main surface of a synthetic quartz glass substrate, which is manufactured by setting them on the same tray. Substrate) was used. The transmittance and phase difference of the phase shift film were measured by taking out the substrate with the phase shift film (dummy substrate) from the chamber before forming the etching mask film. As a result, the transmittance was 27.0% (wavelength: 405 nm), and the phase difference was 178 degrees (wavelength: 405 nm).
Further, the flatness change of the phase shift film was measured using UltraFLAT 200M (manufactured by Corning TOPEL), and the film stress was calculated to be 0.21 GPa. The phase shift film 30 has a small amount of change in transmittance and a small amount of change in phase difference with respect to the chemicals (sulfuric acid hydrogen peroxide, ammonia hydrogen peroxide, ozone water) used for cleaning the phase shift mask, and has high chemical resistance and cleaning resistance. Had.

Further, the film surface reflectance and the optical density of the obtained phase shift mask blank were measured with a spectrophotometer SolidSpec-3700 manufactured by Shimadzu Corporation. The film surface reflectance of the phase shift mask blank (etching mask film 40) was 8.3% (wavelength: 436 nm), and the optical density OD was 4.0 (wavelength: 436 nm). It was found that this etching mask film functions as a light-shielding film having a low reflectance on the film surface.

Further, the obtained phase shift mask blank 10 was subjected to composition analysis in the depth direction by X-ray photoelectron spectroscopy (XPS). FIG. 8 shows the composition analysis result in the depth direction by XPS with respect to the phase shift mask blank of Example 2. FIG. 8 shows the composition analysis results of the etching mask film 40 on the phase shift film 30 side and the phase shift film 30 in the phase shift mask blank. The horizontal axis of FIG. 8 shows the depth (nm) of the phase shift mask blank 10 in terms of SiO ₂ with respect to the outermost surface of the etching mask film 40, and the vertical axis shows the content rate (atomic%). In FIG. 8, each curve shows the change in the content of silicon (Si), nitrogen (N), oxygen (O), carbon (C), chromium (Cr), and molybdenum (Mo), respectively.

As shown in FIG. 8, in the composition analysis result in the depth direction by XPS with respect to the phase shift mask blank 10, the interface between the phase shift film 30 and the etching mask film 40 (transition from the phase shift film 30 toward the etching mask film 40). The ratio of the metal decreases and the content of the transition metal becomes 0 atomic% for the first time), and the ratio of chromium decreases from the etching mask film 40 toward the phase shift film 30, and the content of chromium becomes 0 atom for the first time. In the composition gradient region, which is a region up to the% position, the proportion of oxygen from the interface between the phase shift film 30 and the etching mask film 40 increased in the depth direction and then decreased.
Further, FIG. 10 is a diagram showing the ratio of O / Si (oxygen content ratio to silicon) in the depth direction by XPS to the phase shift mask blanks of Examples 2 and 3. As shown in FIG. 10, the maximum value of the oxygen content ratio to silicon over the region at a depth of 10 nm from the interface between the phase shift film 30 and the etching mask film 40 is 2.0, which is 3.0 or less. rice field.

From the disappearance of chromium (Cr) caused by the etching mask film 40 to the appearance of the oxygen (O) peak caused by the transparent substrate 20 (before the molybdenum (Mo) caused by the phase shift film 30 sharply decreases). In the uniform composition region of the phase shift film 30 of), the molybdenum (Mo) content is 8 atomic% on average, the silicon (Si) content is 40 atomic% on average, and the nitrogen (N) content is 46 atomic% on average. , The content of oxygen (O) was 6 atomic% on average. In the phase shift film 30, the fluctuation of the molybdenum (Mo) content is the smallest, 2 atomic% or less, then the fluctuation of the silicon (Si) content is 3 atomic% or less, and the fluctuation of the nitrogen (N) content. Was 4 atomic% or less, and the fluctuation of the oxygen (O) content was 5 atomic% or less.

B. Phase shift mask and its manufacturing method Using the phase shift mask blank manufactured as described above, a phase shift mask was manufactured by the same method as in Example 1.
The cross section of the obtained phase shift mask was observed with a scanning electron microscope. FIG. 9 is a cross-sectional photograph of the phase shift mask of the second embodiment.

As shown in FIG. 9, the phase shift film pattern formed on the phase shift mask of Example 2 has a cross-sectional shape close to vertical that can sufficiently exert the phase shift effect. Further, in the phase shift film pattern, no penetration was observed at either the interface with the etching mask film pattern and the interface with the substrate. In addition, it had a phase shift film pattern with a small hem width and small CD variation. Specifically, the cross section of the phase shift film pattern is composed of the upper surface, the lower surface and the side surface of the phase shift film pattern. In the cross section of this phase shift film pattern, the angle formed by the portion where the upper surface and the side surface are in contact (upper side) and the portion where the side surface and the lower surface are in contact (lower side) is 74 degrees. Therefore, a phase shift mask having an excellent phase shift effect in an exposure light containing light in a wavelength range of 300 nm or more and 500 nm or less, more specifically, a composite light including i-line, h-line and g-line. Obtained.
The CD variation was as good as 0.092 μm.
In addition, in the cross section of the phase shift film pattern of Example 2, the angle between the portion where the upper surface and the side surface are in contact (upper side) and the portion where the side surface and the lower surface are in contact (lower side) is 74 degrees, which is due to overetching. It exceeded the lower limit of 45 degrees, which allows cross-section control. Therefore, when the phase shift film pattern of Example 2 is formed, it is possible to further verticalize the cross-sectional shape by performing overetching.
Therefore, when the phase shift mask of Example 2 is set on the mask stage of the exposure apparatus and exposure-transferred to the resist film on the display apparatus, it can be said that a fine pattern of less than 2.0 μm can be transferred with high accuracy. ..

Example 3.
A. Phase shift mask blank and its manufacturing method In order to manufacture the phase shift mask blank of Example 3, a synthetic quartz glass substrate of 1214 size (1220 mm × 1400 mm) was prepared as the transparent substrate 20 in the same manner as in Example 1.
In order to form the phase shift film 30 on the main surface of the transparent substrate 20, first, with a predetermined degree of vacuum in the first chamber of the in-line type sputtering apparatus, argon (Ar) gas and helium (He) gas are used. A mixed gas (Ar: 18 sccm, He: 50 sccm, N ₂ : 13 sccm, NO: 4 sccm) containing nitrogen (N ₂ ) gas and nitrogen monoxide gas (NO) was introduced, and the first gas containing molybdenum and silicon was introduced. Oxidation of molybdenum silicide containing molybdenum, silicon, oxygen and nitrogen on the main surface of the transparent substrate 20 by reactive sputtering by applying a sputter power of 7.6 kW to the sputter target (molybdenum: silicon = 1: 9). Nitride was deposited. Then, a phase shift film 30 having a film thickness of 140 nm was formed. Then, after forming the phase shift film 30 on the transparent substrate 20, the phase shift film 30 is taken out from the chamber, and the surface of the phase shift film 30 is surface-treated with an alkaline aqueous solution under the same conditions as in Example 1. rice field.

Next, in the same manner as in Example 1, an etching mask film 40 having a laminated structure of a CrN layer, a CrC layer, and a CrCON layer was formed on the phase shift film 30.
In this way, a phase shift mask blank 10 in which the phase shift film 30 and the etching mask film 40 were formed on the transparent substrate 20 was obtained.

The transmittance and phase difference of the obtained phase shift mask blank phase shift film were measured by MPM-100 manufactured by Lasertec. For the measurement of the transmittance and phase difference of the phase shift film, a substrate with a phase shift film (dummy) in which the phase shift film 30 is formed on the main surface of a synthetic quartz glass substrate, which is manufactured by setting them on the same tray. Substrate) was used. The transmittance and phase difference of the phase shift film were measured by taking out the substrate with the phase shift film (dummy substrate) from the chamber before forming the etching mask film. As a result, the transmittance was 33.0% (wavelength: 365 nm) and the phase difference was 169 degrees (wavelength 365 nm).
Further, the flatness change of the phase shift film was measured using UltraFLAT 200M (manufactured by Corning TOPEL), and the film stress was calculated to be 0.26 GPa. The phase shift film 30 has a small amount of change in transmittance and a small amount of change in phase difference with respect to the chemicals (sulfuric acid hydrogen peroxide, ammonia hydrogen peroxide, ozone water) used for cleaning the phase shift mask, and has high chemical resistance and cleaning resistance. Had.

Further, the film surface reflectance and the optical density of the obtained phase shift mask blank were measured with a spectrophotometer SolidSpec-3700 manufactured by Shimadzu Corporation. The film surface reflectance of the phase shift mask blank (etching mask film 40) was 8.3% (wavelength: 436 nm), and the optical density OD was 4.0 (wavelength: 436 nm). It was found that this etching mask film functions as a light-shielding film having a low reflectance on the film surface.
Further, the obtained phase shift mask blank 10 was subjected to composition analysis in the depth direction by X-ray photoelectron spectroscopy (XPS). FIG. 11 shows the composition analysis result in the depth direction by XPS with respect to the phase shift mask blank of Example 3. FIG. 11 shows the composition analysis results of the etching mask film 40 on the phase shift film 30 side and the phase shift film 30 in the phase shift mask blank. The horizontal axis of FIG. 11 shows the depth (nm) of the phase shift mask blank 10 in terms of SiO ₂ with respect to the outermost surface of the etching mask film 40, and the vertical axis shows the content rate (atomic%). In FIG. 8, each curve shows the change in the content of silicon (Si), nitrogen (N), oxygen (O), carbon (C), chromium (Cr), and molybdenum (Mo), respectively.

As shown in FIG. 11, in the composition analysis result in the depth direction by XPS with respect to the phase shift mask blank 10, the interface between the phase shift film 30 and the etching mask film 40 (transition from the phase shift film 30 toward the etching mask film 40). The ratio of the metal decreases and the content of the transition metal becomes 0 atomic% for the first time), and the ratio of chromium decreases from the etching mask film 40 toward the phase shift film 30, and the content of chromium becomes 0 atom for the first time. In the composition gradient region, which is a region up to the% position, the proportion of oxygen from the interface between the phase shift film 30 and the etching mask film 40 increased in the depth direction and then decreased.
Further, as shown in FIG. 10, the maximum value of the oxygen content ratio to silicon in the region from the interface between the phase shift film 30 and the etching mask film 40 to a depth of 10 nm is 2.4, which is 3.0 or less. Met.

From the disappearance of chromium (Cr) caused by the etching mask film 40 to the appearance of the oxygen (O) peak caused by the transparent substrate 20 (before the molybdenum (Mo) caused by the phase shift film 30 sharply decreases). In the uniform composition region of the phase shift film 30 of), the molybdenum (Mo) content is 7 atomic% on average, the silicon (Si) content is 38 atomic% on average, and the nitrogen (N) content is 46 atomic% on average. , The content of oxygen (O) was 9 atomic% on average. In the phase shift film 30, the fluctuation of the molybdenum (Mo) content is the smallest, 1 atomic% or less, then the fluctuation of the silicon (Si) content is 2 atomic% or less, and the fluctuation of the oxygen (O) content. Was 3 atomic% or less, and the fluctuation of the nitrogen (N) content was 4 atomic% or less.

B. Phase shift mask and its manufacturing method Using the phase shift mask blank manufactured as described above, a phase shift mask was manufactured by the same method as in Example 1.
The cross section of the obtained phase shift mask was observed with a scanning electron microscope. FIG. 12 is a cross-sectional photograph of the phase shift mask of the third embodiment.

As shown in FIG. 12, the phase shift film pattern formed on the phase shift mask of Example 3 had a cross-sectional shape close to vertical that could sufficiently exert the phase shift effect. Further, in the phase shift film pattern, no penetration was observed at either the interface with the etching mask film pattern and the interface with the substrate. In addition, it had a phase shift film pattern with a small hem width and small CD variation. Specifically, the cross section of the phase shift film pattern is composed of the upper surface, the lower surface and the side surface of the phase shift film pattern. In the cross section of this phase shift film pattern, the angle formed by the portion where the upper surface and the side surface are in contact (upper side) and the portion where the side surface and the lower surface are in contact (lower side) is 79 degrees. Therefore, a phase shift mask having an excellent phase shift effect in an exposure light containing light in a wavelength range of 300 nm or more and 500 nm or less, more specifically, a composite light including i-line, h-line and g-line. Obtained.
The CD variation was as good as 0.094 μm.
In addition, in the cross section of the phase shift film pattern of Example 3, the angle between the portion where the upper surface and the side surface are in contact (upper side) and the portion where the side surface and the lower surface are in contact (lower side) is 79 degrees, and the angle is 79 degrees. It exceeded the lower limit of 45 degrees, which allows cross-section control. Therefore, when the phase shift film pattern of Example 2 is formed, it is possible to further verticalize the cross-sectional shape by performing overetching.
Therefore, when the phase shift mask of Example 2 is set on the mask stage of the exposure apparatus and exposure-transferred to the resist film on the display apparatus, it can be said that a fine pattern of less than 2.0 μm can be transferred with high accuracy. ..

Comparative example 1.
A. Phase shift mask blank and its manufacturing method In order to manufacture the phase shift mask blank of Comparative Example 1, a 1214 size (1220 mm × 1400 mm) synthetic quartz glass substrate was prepared as a transparent substrate in the same manner as in Example 1.
The synthetic quartz glass substrate was carried into the chamber of the in-line sputtering apparatus by the same method as in Example 1. The same sputtering target material as in Example 1 was used as the first sputtering target, the second sputtering target, the third sputtering target, and the fourth sputtering target.
Then, after forming the phase shift film on the transparent substrate, it was taken out from the chamber and the surface of the phase shift film was washed with pure water. The pure water cleaning conditions were a temperature of 30 degrees and a surface treatment time of 300 seconds.
Then, an etching mask film was formed by the same method as in Example 1.
In this way, a phase shift mask blank in which the phase shift film and the etching mask film were formed on the transparent substrate was obtained.

The transmission rate and phase difference of the obtained phase shift mask blank phase shift film (phase shift film obtained by cleaning the surface of the phase shift film with pure water) were measured by MPM-100 manufactured by Lasertec. For the measurement of the transmittance and phase difference of the phase shift film, a substrate with a phase shift film (dummy) in which the phase shift film 30 is formed on the main surface of a synthetic quartz glass substrate, which is manufactured by setting them on the same tray. Substrate) was used. The transmittance and phase difference of the phase shift film were measured by taking out the substrate with the phase shift film (dummy substrate) from the chamber before forming the etching mask film. As a result, the transmittance was 20.0% (wavelength: 365 nm) and the phase difference was 176 degrees (wavelength: 365 nm). The film thickness of the phase shift film subjected to the pure water cleaning treatment decreased from the film thickness immediately after the film formation to 198 nm.
Further, the flatness change of the phase shift film was measured using UltraFLAT 200M (manufactured by Corning TOPEL), and the film stress was calculated to be 0.46 GPa. The phase shift film 30 has a small amount of change in transmittance and a small amount of change in phase difference with respect to the chemicals (sulfuric acid hydrogen peroxide, ammonia hydrogen peroxide, ozone water) used for cleaning the phase shift mask, and has high chemical resistance and cleaning resistance. Had.

Further, the film surface reflectance and the optical density of the obtained phase shift mask blank were measured with a spectrophotometer SolidSpec-3700 manufactured by Shimadzu Corporation. The film surface reflectance of the phase shift mask blank (etching mask film) was 8.3% (wavelength: 436 nm), and the optical density OD was 4.0 (wavelength: 436 nm). It was found that this etching mask film functions as a light-shielding film having a low reflectance on the film surface.

Further, the obtained phase shift mask blank was subjected to composition analysis in the depth direction by X-ray photoelectron spectroscopy (XPS). FIG. 5 shows the composition analysis result in the depth direction by XPS with respect to the phase shift mask blank of Comparative Example 1. FIG. 5 shows the composition analysis results of the etching mask film 40 on the phase shift film 30 side and the phase shift film 30 in the phase shift mask blank. The horizontal axis of FIG. 5 shows the depth (nm) of the phase shift mask blank in terms of SiO ₂ with respect to the outermost surface of the etching mask film 40, and the vertical axis shows the content rate (atomic%). In FIG. 5, each curve shows changes in the content of silicon (Si), nitrogen (N), oxygen (O), carbon (C), chromium (Cr), and molybdenum (Mo), respectively.

As shown in FIG. 5, in the composition analysis result in the depth direction by XPS with respect to the phase shift mask blank, the ratio of oxygen due to the phase shift film increases sharply in the depth direction in the above-mentioned composition gradient region. After that, the ratio remained substantially constant, which was equivalent to the ratio of oxygen in the above-mentioned uniform composition region.
Further, as shown in FIG. 7, the maximum value of the oxygen content ratio to silicon in the region at a depth of 10 nm from the interface between the phase shift film and the etching mask film is 6.4, which is a region exceeding 3.0. Was present. It should be noted that molybdenum, silicon, nitrogen, and molybdenum, silicon, and nitrogen in the uniform composition region of the phase shift film 30 from the disappearance of chromium (Cr) caused by the etching mask film 40 to the appearance of the oxygen (O) peak caused by the transparent substrate 20. The oxygen and carbon contents were almost the same as in Example 1.

B. Phase shift mask and its manufacturing method Using the phase shift mask blank manufactured as described above, a phase shift mask was manufactured by the same method as in Example 1.
The cross section of the obtained phase shift mask was observed with a scanning electron microscope. FIG. 6 is a cross-sectional photograph of the phase shift mask of Comparative Example 1.

As shown in FIG. 6, the phase shift film pattern formed on the phase shift mask of Comparative Example 1 had a linear tapered shape. In the cross section of this phase shift film pattern, the angle formed by the portion where the upper surface and the side surface are in contact (upper side) and the portion where the side surface and the lower surface are in contact (lower side) is 5 degrees. Therefore, the obtained phase shift mask has sufficient phase in the exposure light containing light in the wavelength range of 300 nm or more and 500 nm or less, more specifically, the exposure light of composite light including i-line, h-line and g-line. No shift effect can be obtained.
The CD variation was 0.230 μm.
In the cross section of the phase shift film pattern of Comparative Example 1, the angle between the portion where the upper surface and the side surface are in contact (upper side) and the portion where the side surface and the lower surface are in contact (lower side) is 5 degrees, and the cross section is formed by overetching. It was below the lower limit of 45 degrees for which control was possible. Therefore, when forming the phase shift film pattern of Comparative Example 1, it cannot be expected that the cross-sectional shape is further verticalized by performing overetching.
Therefore, when the phase shift mask of Comparative Example 1 is set on the mask stage of the exposure apparatus and exposure-transferred to the resist film on the display apparatus, it is expected that a fine pattern smaller than 2.0 μm cannot be transferred. ..

Further, as shown in FIG. 7, the oxygen content ratio to silicon over the region at a depth of 10 nm from the interface between the phase shift film 30 and the etching mask film 40 was more than 3.0 in each case. ..
Considering these points and the fact that the compositions of Example 1 and Comparative Example 1 in the uniform composition region are substantially the same, oxygen for silicon in the region at a depth of 10 nm from the interface between the phase shift film and the etching mask film is taken into consideration. It can be said that the content ratio of 3.0 or less is an important factor for obtaining a phase shift mask blank having a high transmittance capable of patterning a phase shift film into a cross-sectional shape capable of sufficiently exhibiting the phase shift effect. ..

In the above-mentioned examples, the case where molybdenum is used as the transition metal has been described, but the same effect as described above can be obtained even in the case of other transition metals.
Further, in the above-described embodiment, examples of the phase shift mask blank for manufacturing the display device and the phase shift mask for manufacturing the display device have been described, but the present invention is not limited to this. The phase shift mask blank and the phase shift mask of the present invention can also be applied to semiconductor device manufacturing, MEMS manufacturing, printed substrate and the like.
Further, in the above-described embodiment, an example in which the size of the transparent substrate is 8092 size (800 mm × 920 mm × 10 mm) has been described, but the present invention is not limited to this. In the case of a phase shift mask blank for manufacturing a display device, a large size transparent substrate is used, and the size of the transparent substrate has a side length of 300 mm or more. The size of the transparent substrate used for the phase shift mask blank for manufacturing a display device is, for example, 330 mm × 450 mm or more and 2280 mm × 3130 mm or less.
Further, in the case of a phase shift mask blank for semiconductor device manufacturing, MEMS manufacturing, and a printed circuit board, a small transparent substrate is used, and the size of the transparent substrate is 9 inches or less on a side. be. The size of the transparent substrate used for the phase shift mask blank for the above application is, for example, 63.1 mm × 63.1 mm or more and 228.6 mm × 228.6 mm or less. Normally, 6025 size (152 mm x 152 mm) and 5009 size (126.6 mm x 126.6 mm) are used for semiconductor manufacturing and MEMS manufacturing, and 7012 size (177.4 mm x 177.4 mm) for printed circuit boards. , 9012 size (228.6 mm × 228.6 mm) is used.

10 ... Phase shift mask blank, 20 ... Transparent substrate, 30 ... Phase shift film,
30a ... phase shift film pattern, 40 ... etching mask film,
40a ... First etching mask film pattern,
40b ... 2nd etching mask film pattern, 50 ... 1st resist film pattern,
60 ... Second resist film pattern, 100 ... Phase shift mask

Claims (11)

A phase shift mask blank having a phase shift film on a transparent substrate and an etching mask film on the phase shift film.
The phase shift mask blank uses an etching mask film pattern in which a desired pattern is formed on the etching mask film as a mask, and the phase shift film is wet-etched to have a phase shift film pattern on the transparent substrate. It is the original plate for forming
The phase shift film contains a transition metal, silicon, and oxygen, and the oxygen content is 5 atomic% or more and 70 atomic% or less.
A composition gradient region is formed at the interface between the phase shift film and the etching mask film, and in the composition gradient region, the proportion of oxygen is gradually and / or continuously increased in the depth direction. Including area
A phase shift mask blank characterized in that the content ratio of oxygen to silicon over a region at a depth of 10 nm from the interface between the phase shift film and the etching mask film is 3.0 or less. The phase shift mask blank according to claim 1, wherein the phase shift film is composed of a plurality of layers. The phase shift mask blank according to claim 1, wherein the phase shift film is composed of a single layer. The phase shift mask blank according to any one of claims 1 to 3, wherein the phase shift film contains nitrogen. The phase shift mask blank according to claim 4, wherein the phase shift film has a nitrogen content of 2 atomic% or more and 60 atomic% or less. The phase shift mask blank according to any one of claims 1 to 5, wherein the film stress of the phase shift film is 0.2 GPa or more and 0.8 GPa or less. The phase shift mask blank according to any one of claims 1 to 6, wherein the etching mask film is made of a chromium-based material. The phase shift mask blank according to any one of claims 1 to 7, wherein the etching mask film contains at least one of nitrogen, oxygen, and carbon. The phase shift mask blank according to any one of claims 1 to 8, wherein the transparent substrate is a rectangular substrate, and the length of the short side of the transparent substrate is 300 mm or more. The step of preparing the phase shift mask blank according to any one of claims 1 to 9, and the step of preparing the phase shift mask blank.
The step of forming a resist film on the phase shift mask blank and
A resist film pattern is formed by drawing and developing a desired pattern on the resist film, and the etching mask film is patterned by wet etching using the resist film pattern as a mask to form the etching mask film pattern. And the process to do
A method for manufacturing a phase shift mask, which comprises a step of forming a phase shift film pattern on the transparent substrate by wet etching the phase shift film using the etching mask film pattern as a mask. A phase shift mask manufactured by using the phase shift mask manufactured by using the phase shift mask blank according to any one of claims 1 to 9, or by the method of manufacturing a phase shift mask according to claim 10. A method for manufacturing a display device, which comprises a step of exposing and transferring a transfer pattern to a resist film on the display device.

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